1. Field of the Invention
The invention concerns a device for measuring the surface of a print product.
Such devices are used to determine the optical density of the different printing inks applied and generally have a measuring head which can be moved over the finished print product and determines the optical density of the different colour separations.
2. Disclosure of Relevant Art
Although, in modern printing machines, the ink films of the print products are dried by exposure to heat or light radiation so that the print products do not have to be dried in racks, even after such irradiation the printing inks are still somewhat tacky, so that print products stacked on top of each other can stick together. To prevent this, the upper surface of the print product is frequently dusted over with a fine powder, which may, for example, be finely ground mineral material or finely ground starch. The quantity of the powder mass applied is set on the dusting device according to empirical values and with continuous monitoring of the dusted products. However, with a more precise knowledge of the quantity of the powder mass actually obtained on the print product, it would be possible in many cases to reduce the powder delivery on the dusting device, i.e., to work with a smaller surplus. This would be advantageous not only in terms of a saving in powder, but it would also be possible in this way to prevent powder deposits in the printing machine which can result from the delivery of excessive powder.